1. Field of the Invention
The present invention relates generally to pneumatic tires, and more particularly, but not by way of limitation, to pneumatic tires especially designed for use with telescopic material handlers.
2. Description of the Prior Art
Telescopic material handlers are forklift trucks commonly utilized on construction sites. They include a telescoping boom typically with a reach of from 30 to 40 feet, and they can steer in a forward steer or rear steer mode, and also in four wheel steer, crab or crawl modes. Telescopic material handlers must be capable of maneuvering in tight places and they have severe steer angles as high as 86 to 88 degrees at the steered wheels.
Because telescopic material handlers are used on construction sites, they encounter rough terrain littered with much debris such as nails, piles of lumber, broken concrete blocks and the like.
Additionally, because much of such equipment is provided by rental services to the construction contractors, the operators of the telescopic material handlers are often inexperienced drivers.
All of these factors combine to result in a scenario where the tires utilized on the telescopic material handlers can be expected to encounter substantial tire injury due to running over and against debris, sideswiping curbs and other abutments, and backing into obstacles. Many of these tire injuries, particularly the sideswiping of curbs and the like, typically injure the tire at the widest point of the sidewall which is usually near the mid height of the sidewall.
Currently, most telescopic material handlers utilize 24 or 25 inch diameter wheel rims and use tires originally designed for use on road graders and having a tire outside diameter of approximately 51 inches. Typical examples of such current tires produced by the assignee of the present invention include the Bridgestone Model VUT G-2 tire in a 13.00 R 24 size, the Bridgestone Model L-3 tire in a 13.00-24 size and a Firestone Model SGG RB G-2 or G2/L2 tire in a 13.00-24 size. The aspect ratio of these tires, which is defined as the ratio of sidewall height to the total width of the tire as a percentage, is typically relatively high, well in excess of 90 percent and in some cases near 100 percent.
Another typical prior art tire commonly used on telescopic material handlers is the Solideal Model TG tire in a 13.00-24 size which has an overall diameter of 51.1 inches and a section width of 14.4 inches. The Solideal tire also has a relatively high aspect ratio of approximately 96.1 percent. The Solideal 13.00-24 TG tire is advertised as having extra sidewall protection to resist road abuse, and it achieves this by relieving the sidewall area along a wide band at near mid sidewall height and thickening the area above and below the relieved area.
Another approach to providing sidewall protection for construction vehicle tires is shown in U.S. Pat. No. 6,666,248 to Omoto et al. which discloses the use of convex shape sidewall protectors embedded in the sidewall along the midline of the sidewall.
Thus it is seen that there is a continuing need for an effective, economical design for a pneumatic tire especially intended for use on telescopic material handlers which provides improved sidewall protection.